Proof of work will stop most potential attackers (people with only a few computers under their control) from doing massive flooding, but it isn't the ideal solution and powerful attackers (people with botnets) can easily get around it. That is a possible solution as well, however we need to think of the anonymity implications of a server being able to censor some of the information it holds. It would be better to have some cryptographic way of solving this problem rather than sheer brute content availability. this paper looks interesting: https://www.usenix.org/conference/foci12/one-way-indexing-plausible-deniability-censorship-resistant-storage So after reading the abrtract it sounds like this might be what we want, I need to read the rest of the paper though. It looks like it has all the functionality of encrypted keyword search (search by keyword, servers cannot determine the keyword searched for), private stream searching (same as EKS plus servers cannot tell the content returned), and the censorship resistance we were looking for (servers can obtain content from the network and still not be able to determine that they host the content as well). So maybe need to start saying OWI (one way indexing) instead of PSS instead of EKS heh.